Blender file selector support for setting multiple selected files/dirs which operators can use.

This allows the sequencers Add-Image strip to work like it does in 2.4x.

- as well as setting the "filename" operator property, operators can have collections called "files" and "dirs" which are set when available.
- RNA_OperatorFileListElement as new collection type, its a bit redundant since each item only has a "name" property but its needed since we don't have a string array type.
- the file selector now prints operators it runs.

Tested with python, adding a list of images works to the sequencer works.
bpy.ops.SEQUENCER_OT_image_strip_add(name="MyImages", start_frame=54, channel=2, filename="/somedir/", replace_sel=True, files=[{"name":"test1.png"}, {"name":"test2.png"}])

source/blender/python/intern/bpy_interface.c

@@ -19,6 +19,7 @@
 #include "bpy_rna.h"
 #include "bpy_operator.h"
 #include "bpy_ui.h"
+#include "bpy_util.h"
 
 #include "DNA_anim_types.h"
 #include "DNA_space_types.h"